I have bunch of RX480 rigs and even RX570.. GTX1070 will blow them per card for profit. GTX 1070 is better with equihash, Neoscrypt, Lararev2...
Doubt GTX 1070 would do same amount as a RX 570 with bios mod mining Monero. Ethereum will only do about 1 Mhs more per card and that is not guaranteed, dual mine will do the same, the only algorithm where GTX 1070 is better is the Equihash algorithm and will surpass every RX 5xx series. The price is much more expensive for 1070 cards so better to do a bios modification and spend way less for the same performance unless you want to explicitly mine only Zcash.
Not just equihash. Neoscrypt, LyraREv2, Blake, LBRY, Groestl, X11, Pascal, Skunkhash
1070 can surpass bios modded RX480, RX570 in ethash and neck and neck with Cryptonight.
I have 1070 here and bios modded Rx570.. 1070 is more robust card for mining.